Project Summary To better understand the illicit fentanyl risk environment and associated overdose risk, we propose a 3-year ethnographic study in three North Carolina (NC) communities with extremely high opioid overdose mortality rates. America's fentanyl epidemic is evolving too fast for public health authorities to appropriately respond. Fentanyl overdose deaths increased 540% in the U.S. from 2013 to 2016 and outnumbered deaths involving prescription opioids and heroin for the first time in 2016. Pharmaceutical fentanyl is a synthetic, short-acting, opioid analgesic 50 times more potent than heroin and approved for the management of cancer-related pain. Fentanyl's rapid onset and high potency make it a perilous product for illicit consumption. Unregulated drug markets lack the regulatory capacity necessary to ensure product standardization and protect public health and safety from unwitting or unsafe consumption. The swift ascendency of illicit fentanyl has contributed to an increasingly dangerous opioid overdose risk environment characterized by rapid market fluctuation, inconsistent product availability, and unknown and variable purity and potency. Ethnography?consisting of field observations in real-time and in situ conversational interviews with people in their social milieu?is particularly suitable for uncovering information about topics that are relatively unknown, illegal and stigmatized, and where situational developments are fluid and rapidly evolving in real time. Following Zinberg's analytical framework of DRUG, SET and SETTING, this ethnographic study will explore how supply-side (DRUG), individual-level (SET), and environmental factors (SETTING) may be interacting to form an overdose risk environment. The specific aims of the proposed study are: Aim 1: To learn how illicit fentanyl and other illegal and controlled substances are acquired by people who use drugs to identify the ways in which market factors may affect consumption patterns, drug use behaviors, and overdose risk among this population; Aim 2: To examine individual-level factors that may explain illicit fentanyl purchasing decisions, drug consumption patterns, drug injecting mechanics, and overdose risk; and Aim 3: To explore the impact of social, online, and legal environments on the illicit fentanyl market and their influence on fentanyl consumption, drug use behavior, and overdose risk. To achieve these aims, we will conduct ethnographic research in in three, high- burden communities in NC among people who use illicit opioids. Proposed Principal Investigator Dr. Zibbell has developed rapport and gained the trust of our collaborative community-based organization, which operates several syringe service programs in the study sites. These programs will serve as entry-points for participant- observation ethnography of people who use fentanyl and related community members and stakeholders, 60 of whom will also participate in semi-structured qualitative interviews. Findings will provide critical knowledge to better inform the development of future investigations and to help identify supply-side and consumer-level interventions to reduce overdose risk and negative sequelae associated with the illicit fentanyl epidemic.